Wearable electronic devices which may be used to monitor biometric parameters of a user are known. Such devices may be configured to monitor parameters such as heart rate, blood oxygenation, temperature, galvanic skin conductance or any other suitable parameter. These parameters may then be used to track the activity levels of the user or monitor the health and/or well being of the user.
It is useful to provide such devices which are efficient enough to be worn for long periods of the time by the user but which enable efficient capture of the biometric parameter data. It is also useful to be able to associate the information obtained by the device with the identity of the wearer.